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/*

 *  NOTE:  The structure of the routines is identical to that of POSIX

 *         Message_queues to leave the option of having unnamed message

 *         queues at a future date.  They are currently not part of the

 *         POSIX standard but unnamed message_queues are.  This is also

 *         the reason for the apparently unnecessary tracking of

 *         the process_shared attribute.  [In addition to the fact that

 *         it would be trivial to add pshared to the mq_attr structure

 *         and have process private message queues.]

 *

 *         This code ignores the O_RDONLY/O_WRONLY/O_RDWR flag at open

 *         time.

 *

 *  $Id: mqueueopen.c,v 1.2 2001-09-27 11:59:17 chris Exp $

 */

#include <stdarg.h>

#include <pthread.h>

#include <limits.h>

#include <errno.h>

#include <fcntl.h>

#include <mqueue.h>

#include <rtems/system.h>

#include <rtems/score/watchdog.h>

#include <rtems/posix/seterr.h>

#include <rtems/posix/mqueue.h>

#include <rtems/posix/time.h>

/*PAGE

 *

 *  15.2.2 Open a Message Queue, P1003.1b-1993, p. 272

 */

mqd_t mq_open(

  const char *name,

  int         oflag,

  ...

  /* mode_t mode, */

  /* struct mq_attr  attr */

)

{

  va_list                        arg;

  mode_t                         mode;

  struct mq_attr                *attr = NULL;

  int                            status;

  Objects_Id                     the_mq_id;

  POSIX_Message_queue_Control   *the_mq;

  Objects_Locations              location;

  _Thread_Disable_dispatch();

  if ( oflag & O_CREAT ) {

    va_start(arg, oflag);

    mode = (mode_t) va_arg( arg, mode_t );

    attr = (struct mq_attr *) va_arg( arg, struct mq_attr * );

    va_end(arg);

  }

  status = _POSIX_Message_queue_Name_to_id( name, &the_mq_id );

  /*

   *  If the name to id translation worked, then the message queue exists

   *  and we can just return a pointer to the id.  Otherwise we may

   *  need to check to see if this is a "message queue does not exist"

   *  or some other miscellaneous error on the name.

   */

  if ( status ) {

    /*

     * Unless provided a valid name that did not already exist

     * and we are willing to create then it is an error.

     */

    if ( !( status == ENOENT && (oflag & O_CREAT) ) ) {

      _Thread_Enable_dispatch();

      set_errno_and_return_minus_one_cast( status, mqd_t );

    }

  } else {                /* name -> ID translation succeeded */

    /*

     * Check for existence with creation.

     */

    if ( (oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL) ) {

      _Thread_Enable_dispatch();

      set_errno_and_return_minus_one_cast( EEXIST, mqd_t );

    }

    /*

     * XXX In this case we need to do an ID->pointer conversion to

     *     check the mode.   This is probably a good place for a subroutine.

     */

    the_mq = _POSIX_Message_queue_Get( the_mq_id, &location );

    the_mq->open_count += 1;

    _Thread_Enable_dispatch();

    _Thread_Enable_dispatch();

    return (mqd_t)the_mq->Object.id;

  }

  /*

   *  At this point, the message queue does not exist and everything has been

   *  checked. We should go ahead and create a message queue.

   */

  status = _POSIX_Message_queue_Create_support(

    name,

    TRUE,         /* shared across processes */

    oflag,

    attr,

    &the_mq

  );

  /*

   * errno was set by Create_support, so don't set it again.

   */

  _Thread_Enable_dispatch();

  if ( status == -1 )

    return (mqd_t) -1;

  return (mqd_t) the_mq->Object.id;

}